Distortionless heated impression cylinder



July 9. 1963 M.EBNETER DISTORTIONLESS HEATED iMPRE SSION CYLINDER Filed Dec. 5, 1965 F G. 3 PRIOR ART INVENTOR. MARfl/S iBNETER A T TORUEKI.

United States Patent 3 Claims. of. 101- 407 This invention relates in general to the construction of an impression cylinder of printing machines and more particularly to the construction of an impression cylinder of a multi-colour printing machine with means for heating the circumferential wall or jacket, constructed and arranged to overcome any tendency for cylinder distortion.

The impression cylinder jacket of which may be heated by one or a plurality of heaters, particularly electric radiators, arranged inside the cylinder. The cylinder is constructed so that the cylinder jacket may be heated without being distorted so that it will not become uneven and noncircular to the extent that the complete cylinder eventually breaks because of unequal stress and extension of the material of the cylinder under the effect of heat.

There are known methods and devices for printing of a plurality of colours on a paper web, in particular by using aniline dyes. Such Web'colour presses preferably have a plurality of form cylinders mounted around a comparatively large impression cylinder. When using such machines the paper web is guided around the comparatively large impression cylinder and successively printed by the form cylinders arranged around the impression cylinder. Such web colour presses and methods for the printing of multi-colour prints are also used for the printing of pressure sensitive adhesive tapes for the manufacture of pressure sensitive labels arranged on a release liner. In manufacturing such pressure sensitive labels, a Web of pressure sensitive label stock is printed by a plurality of form cylinders arranged around a comparatively large impression cylinder. Thereafter the label stock is die-cut, for example by circular knives or other rotative dies for imparting or cutting a desired shape, form or finish from the material, whereafter the matrix is immediately drawn from the release liner.

When manufacturing such pressure sensitive labels glued to a release liner it has been found advantageous, particularly when aniline colours were used for printing, to provide means for the immediate drying of the colours on the paper web before the web is die-cut to avoid that the print is damaged or smeared by the following process. It has further been found advantageous to heat the label stock after printing to provide the pressure sensitive adhesive, particularly when thermoplastic material is used, becoming heated to facilitate the removal of the matrix.

There are known machines for the manufacture of strips of pressure sensitive labels, whereby after printing of the paper web the web is drawn over a heated plate, the plate being flat or convex to provide immediate drying of the colour and heating of the adhesive and plasticizing thereof. It is for technical and economical reasons that such heated plates may not be very long and therefore such plates must be heated up to a relatively high temperature. Such relatively high temperatures may adversely affect the paper web in particular by causing the scorching of the web when the machine is stopped for any reasons whatsoever.

To avoid these disadvantages it has been tried to heat the relatively large impression cylinder. The paper web is trained to run around substantially the complete circum- "ice ference of the cylinder without being moved relative to the rotating cylinder. It has been found that the cylinder need not be heated to the temperatures required for the above mentioned heating plate.

It has, however, been found that despite the relatively low heating of the cylinder jacket by heaters arranged between the wheel spokes the cylinder is unequally heated and becomes noncircular by the unequal expansion of the material. This has also been found when spoke-reinforced disk wheels were used. When using disk wheels the reinforcement by spokes could not be abandoned because disk wheels do not guarantee quiet running of the wheel bearing a heavy jacket in case of high speed rotation. It has further been found that in case of relatively high heating many constructions were endangered by a breaking of the wheel or the spokes caused by the unequal expansion of the material caused by unequal heating of the wheel and the cylinder jacket. Further in any case any unevenness or distortion of the cylinder jacket has been found extremely disadvantageous because as a rule there appear compass difiierences between a plurality of prints when printed on a distorted or noncircular impression cylinder.

It is an object of the invention to provide an impression cylinder which may be heated without becoming noncircular or uneven and which will not rupture at high speed rotation although the heating is essentially restricted to the jacket. The above mentioned disadvantages of such heated impression cylinders are avoided by a Z-shape construction of the jacket and the spoked wheel or a spokereinforced disk Wheel.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a schematic side elevational view of a pressure sensitive label printing machine having an impression cylinder constructed in accordance with the invention;

FIG. 2 is a side elevational view of an impression cylinder with heating means constructed in accordance with the prior art;

FIG. 3 is a section taken on the line 3-3 of the prior art impression cylinder of FIG. 2; and

FIG. 4 is a perspective view, partially in section, of an impression cylinder constructed in accordance with the invention.

Referring to the drawings in particular, the invention provides an improved impression cylinder 1 for use preferably in a system for printing pressure-sensitive labels using a rotary printing and stamping apparatus. As indicated in FIG. 1, a paper web 4 is guided over a guiding roller 5 to the impression cylinder 1. The impression cylinder 1 is rotated along with the web 4 past a plurality of separate aniline color form cylinders 2, 2, 2 which are arranged at spaced locations around the periphery of the impression cylinder. Each form cylinder 2 is associated with its own color reservoir and feeding roller system. The three aniline form cylinders Z, 2, 2 imprint the web 4 as it is moved around on the surface of the impression roller 1. The printed web 4 is. then guided into a cutting mechanism 3 and the waste grid material or mat ix 7 of the web is moved around and rolled up on a roller 8. The imprinted and cut web is then delivered outwardly in the direction of the arrow indicated.

As indicated in FlGS. 2 and 3, attempts have been made in the prior art to provide for the heating of the impression cylinder 1 to facilitate drying of the colors by using heating elements such as electric radiating members 9 which are mounted between spokes 20 of the prior art impression cylinder 1'. By associating a heating element 9 with a segment of the impression cylinder, the continuous heat applied by the element would cause the outward distortion of the walls of the impression cylinder 1 to the dotted line position indicated in FIG. 2. Such expansion was accompanied by increase in force exerted on the spokes 20 which in practice leads to the complete distortion of the cylinder.

In accordance with the invention, the impression cylinder 1 of the invention is formed with a central cylindrical hub 11 and an outer annular jacket or peripheral portion 12 which is joined to the hub through a connecting conically disposed web 10. The web 10 extends from one end (e.g. the inner end) of the hub portion 11 to an opposite end of the outer peripheral portion 12. The web is advantageously reinforced by a plurality of equally spaced spoke elements 14 of substantially triangular configuration. An inwardly projecting lip 13 is formed at the inner end of the jacket 12 and provides a counter-balancing distribution of the material of the cylinder 1.

In the arrangement indicated it has been found preferable to provide either one or a plurality of heaters arranged in a ring 9' between the web portion 10 and the lip 13. It has been found that when the impression cylinder 1 is made with its one half portion, that is from the hub to the outer jacket formed with a cross section of substantially Z-shaped configuration, and with the heater element 9 disposed in the area between the lip and the web, that an even heating of the impression cylinder 1 would take place over its entire circumference. No uneven heating will take place as in the other embodiment, because the web 10 is made of substantially uniform thickness and there will be no uneven expansion of the web or the jacket 12 and any forces produced by temperature changes will be equal and balanced. The heaters are arranged so that both the 10 and the lip 13, as well as the jacket 12, are within the area of heating or heat radiation from the heaters so that the simultaneous heating and expansion of the material effects a shifting of the jacket 12 substantially parallel to the hub axis. The forces acting on the web caused by the expansion of the circumference of the jacket 10 are easily absorbed by the web 10 without any danger of excess expansion since the truncated conical shape of the web 10 becomes flatter upon expansion. The angle of disposition of the web 10 is regulated in accordance with the material employed, and thus the angle which the web makes with the hub 11 may be varied, as well as the angle which the web makes with the outer jacket 12 may be varied. The extension of the lip 13 is made to an extent to correspond to the material of the web it) so that an equal expansion of the cylinder jacket over its entire width and an exact shifting of the jacket parallel to the axle of the cylinder is assured.

In a preferred arrangement, the impression cylinder 1 is advantageously cast in one piece in order to facilitate the equal expansion of heat and the adjustment of any material tensioned in its formation.

It will be understood that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive, reference being made to the claims rather than to the foregoing description to indicate the scope of the invention.

What I claim is:

1. An impression cylinder construction particularly for use for printing with a plurality of colors on a paper web, comprising a substantially cylindrical hub portion, an annular circumferential jacket portion, a conical web joined between an inner end of said hub portion and an outer end of said circumferential jacket portion, said circumferential jacket portion having an inwardly projecting lip on the end thereof opposite to its connection to said web, and heater means disposed between said lip and said web adjacent said circumferential portion for heating said circumferential portion uniformly.

2. An impression cylinder construction particularly for use for printing with a plurality of colors on a paper web, comprising a substantially cylindrical hub portion, an annular circumferential portion, a conical web joined between an inner end of said hub portion and an outer end of said circumferential portion, the inner end of said circumferential portion having an inwardly projecting lip,

and heater means disposed between said lip and said web adjacent said circumferential portion for heating said circumferential portion uniformly, said impression cylinder having a half-portion cross section which is substantially Z-shaped, and a plurality of radially extending spoke formations between said hub portion and said Web for reinforcing said impression cylinder.

3. An impression cylinder construction particularly for use for printing with a plurality of colors on a paper web, comprising a substantially cylindrical hub portion, an annular circumferential portion, a conical web joined between an inner end of said hub portion and an outer end of said circumferential portion, the inner end of said circumferential portion having an inwardly projecting lip, and heater means disposed between said lip and said web adjacent said circumferential portion for heating said circumferential portion uniformly, said impression cylinder having a half-portion cross section which is substantially Z-shaped and a plurality of spoke formations extending between said hub portion and said web for reinforcing said impression cylinder, said heater means comprising at least one electrical radiator element disposed in the space between said web and said lip and arranged for heating a substantial portion of the periphery of said circumferential portion uniformly.

References Cited UNITED STATES PATENTS 879,731 2/1908 Burns 34108 1,609,377 12/1926 Millspaugh 29-423 2,351,224 6/1944 Nystrom 10136 XR 3,037,106 5/1962 Seney 219471 ROBERT E. PULFREY, Primary Examiner.

J. R. FISHER, Assistant Examiner, 

1. AN IMPRESSION CYLINDER CONSTRUCTION PARTICULARLY FOR USE FOR PRINTING WITH A PLURALITY OF COLORS ON A PAPER WEB, COMPRISING A SUBSTANTIALLY CYLINDRICAL HUB PORTION, AN ANNULAR CIRCUMFERENTIAL JACKET PORTION, A CONICAL WEB JOINED BETWEEN AN INNER END OF SAID HUB PORTION, AND AN OUTER END OF SAID CIRCUMFERENTIAL JACKET PORTION, SAID CIRCUMFERENTIAL JACKET PORTION HAVING AN INWARDLY PROJECTING LIP ON THE END THEREOF OPPOSITE TO ITS CONNECTION TO SAID WEB, AND HEATER MEANS DISPOSED BETWEEN SAID LIP AND SAID WEB ADJACENT SAID CIRCUMFERENTIAL PORTION FOR HEATING SAID CIRCUMFERENTIAL PORTION UNIFORMLY. 